Reply by Chris Wright

Batteries are tricky, I’ve found that some are better then others, and in my experience it’s not always brand specific. I’ve had Porter-Cables that lasted very well, and some that didn’t and so on. The type of battery can also determine the life of the battery. Lithium Ion batteries are some of the best, hold a charge well and tend to not wear out. The down side, they are kinda pricy. One thing you might try with your old batteries, since they are already dead and you’ve got nothing to loose, is what’s refered to as a deep discharge. Hook it up to a small light buld and just let it run till it goes completely dead and then recharge it from that state. That can sometimes “reset” the battery “memory” and allow it to hold a charge better. The other thing I do to prolong the life of my batteries is to remove them from the charger as soon as they are fully charged. That goes for anything with a rechargeable battery (cell phone, laptop, etc.), if the charger keeps pumping juice into the battery it can damage them and shorten their life.